Elevator control system



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f TQQ July 6, 1943. w. F. EAMES 2,323,652

ELEVATOH CONTROL SYSTEM Fned March 12, 1942 2 sheets-sheet 1 6 3 r 5 nu3 M F A' 2 y E 1/mm d z f n e n J 2l 7 W. o $5 mw C y C .T e M a D U P Mw w n. p ull@ a 0.1 um Wl n. Mm n I INVENTOR M/am-fmes.

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w. F. EAMES 2,323,652

ELEVATOR CONTROL SYSTEM Filed March 12, 1942 2 Sheets-Sheet 2 July 6,1943.

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Patented July 6, 1943 ELEVATOR CONTROL SYSTEM William F. Eames.Westfield. N. J., assignor to Westinghouse Electric & ManufacturingCompany, East Pittsburgh, Pa., a corporation of Pennsylvania ApplicationMarch 12, 1942, Serial No. 434,323

(Cl. IS7-29) 9 Claims.

My invention relates to elevator control systems in which the cars arestopped at the floors by suitable automatic means dependent on theposition and operation of the cars with reference to the oors and, moreparticularly, to such systems of this character as are operated atrelatively low speeds of the order of 100 to 150 feet per minute.

Although not limited thereto, my invention is particularly applicable toelevators of the geared-drive type in which the hoisting sheave isdriven through suitable gearing by a constant speed motor, sometimescalled an induction motor. The motors usually provided in suchinstallations have dropping speed-torque characteristics resulting in avariation of the car speed dependent upon the elevator load. If themotor is disconnected and the brake applied at the same fixed distancein advance of the floor each time, the car will coast or drift againstthe retarding torque of the brake for different distances before itstops, depending upon the car load and its direction of operation.Hence, the car may stop level at the floor when bearing one load and maystop short of or beyond the door when bearing other loads, unless somearrangement is provided for varying the distance of the car drift inaccordance with the speed or load.

One object of my invention is to provide a means for causing the controlapparatus of a constant speed elevator motor to cut ofi the motor andapply the brake at varying distances from the iioor in accordance withthe load on the car and its direction of operation, so that the car willcoast or drift into a stop approximately level with the floor landing atwhich it is to load or unload.

Another object is to provide a stopping system for elevator cars whichshall be simple and inexpensive to install, operate and maintain inoperation, and which will be eiective and long lived in service.

A further object is to provide an elevator stopping system which shallstop the cars approximately level with the floor landings withoutrequiring moving parts on the car.

A still further object is to provide an elevator stopping system whichmay be constructed of rugged apparatus which will stand up well underhard usage and which can be easily and inexpensivelyv enclosed andprotected from tampering or damage.

It is also an object to provide a stopping system in which the circuitswill not be overly sensitive to speed, time or temperature changes andin which it will not be necessary to work to close tolerances inadjusting the system for operation.

For a better understanding of my invention, reference may be had to theaccompanying drawings, in which:

Figure 1 is a diagrammatic representation of an elevator installationembodying my invention;

Fig. 2 is a straight-line representation of the power and controlcircuits for the car illustrated in Fig 1;

Fig. 2A is a key representation of the relays embodied in Fig. 2,illustrating the coils and contact members disposed in horizontalalignment with their positions in the straight-line circuits so thattheir locations therein may be readily determined;

Fig, 3 is a diagram of a curve showing the pull of two of the loadrelays embodied in Fig. 2; and

Fig. 4 is a diagram of curves showing the levels made at the stopswithout correction and with correction.

Referring more particularly to the drawings, I have illustrated anelevator car 9 disposed in a hatchway i0 and supported by a cable Ilpassing over a hoisting drum I2 to a suitable counterweight i3. Thehoisting drum is mounted upon a shaft it driven by an electric motor H.A suitable gear reducing mechanism I5 is connected with the shaft i4 tosecure an appropriate speed of the car when the motor H is in operation.A brake il operated by an electromagnetic coil i8 and a spring i9 isprovided for stopping the car and holding it at any floor at which astop is made.

The hoisting motor H is illustrated as a threephase single speedalternating-current motor comprising a stator having windings 2|, 22,and 23 and a rotor 24. The stator windings 2i, 22, and 23 may beconnected to a suitable alternating current supply represented by theconductors Li, L2, and L3 by means of an up direction switch U and adown direction switch D and a car running relay M.

A car switch CS is mounted in the car for starting and stopping it.Rotation of the car switch in clockwise direction will energize the downdirection switch D to connect the motor windings to move the cardownwardly and rotation of the switch in counterclockwise direction willenergize the up direction switch to connect the motor windings to movethe car upwardly. Centering the car switch will cause its stoppingsystem to stop it at the next floor.

The energy for operating the direction switches, the relay M and thestopping system may be supplied through a pair of conductors L+ and L-which are connected for energization through a full-wave rectifier 25and a transformer 26 to the supply conductors Ll and L3.

In order to cause the elevator, when making a stop at a oor, to cut onits motor and apply its brake at a distance from the floor which willhave a definite proportion to the load on the car so that the car willland approximately level with the floor, I have provided a novelstopping system comprising a pair of stopping circuits 21 and 29 forcontrolling the direction switches U and D in making a stop, a pluralityof switching devices such as stopping inductor relays AR, BR and CR foroperating the stopping circuits, and a pair of control relays E and Ffor selectively controlling the effectiveness of the stopping circuitsin accordance with the load on the car when a stop is being made.

The up stopping circuit 29 is connected to the coil of the up directionswitch U in parallel with the up contacts 31 on the car switch CS and isprovided with a shunt circuit 30 around one part and a shunt circuit 3|around another part. The down stopping circuit 21 is connected to thecoil of the down direction switch D in parallel with the down contacts34 on the car switch CS and is `provided with a shunt circuit 32 aroundone part and a shunt circuit 33 around another part. The shunt circuitsare controlled by the control relays E and F. The circuits 21, 29, 30,3|, 32 and 33 may be termed stopping circuits.

The inductor relay AR is mounted on the top of the car and at one sidethereof in position to pass between an up inductor plate AUP and a downinductor plate ADP when the car moves up and down in the hatchway. Therelay has an energizing coil A, a normally closed pair of up contacts AUand a normally closed pair of down contacts AD. The inductor plates areconstructed of magnetic material and are mounted in the hatchway inposition to cooperate with the relay and open its contacts when it is inan energized condition as the car approaches the inductor plates. Theinductor relay BR with its coil B is similar to the relay AR and isdisposed to cooperate with an up inductor plate BUP for opening its upcontacts BU and a down inductor plate BDP for opening its down contactsBD. The inductor relay CR with its coil C is also s'imilar to the relayAR and is disposed to cooperate with an up inductor plate CUP foropening its up contacts CU and a down inductor plate CDP for opening itsdown contacts CD.

Referring to the plates for the third floor, the position of the upplate BUP should be slightly higher than that of the up plate AUP andthe position of the up plate CUP should be slightly higher than that ofthe up plate BUP. The position of the down plate BDP should be lowerthan that of the down plate CDP and the position of the down plate ADPshould be lower than that of the down plate BDP. The distances of theplates from the floor should be predetermined in accordance with thedesign of the car, its loading and its counterweight. The plates ADP2,etc., for the second floor should be disposed in the same relation forthe second iloor.

The plates may be made of light sheet iron welded to a support bracket28 to constitute a unitary structure to be mounted n the Wall 0f thehatchway. In welding the plates on the frame, they may be placed intheir predetermined positions with relation to each other so that whenthe unit is mounted in the hatchway with its position correct for oneplate, the positions of all the plates will be correct and it will notbe necessary to adjust each plate individually.

I have illustrated inductor plates for only two iloors, but it is to beunderstood that similar inductor plates will be mounted at each floor.

The coils A, B and C of the inductor relays are connected in seriesthrough the center contact 35 of the car switch CS so that centering thecar switch will cause all of the inductor relay coils to be energizedsimultaneously for a stop at the next floor.

When the car comes into a floor stop in the up direction with theinductor coils energized, the contacts AU passing plate AUP open rst;later contacts BU passing plate BUP open and nally when the car isnearly at the floor level, the contacts CU passing the plates CUP open.These contacts always operate in this sequence on an up stop and atpredetermined distances from the floor at which the stop is to be madeand they are disposed in series in the up stopping circuit 29.

On a down stop, rst the down contacts CD pass the plate CDP and open.Next, the down contacts BD pass the plate BDP and open, and lastly thecontacts AD pass the down plate ADP and open. Hence, it is seen that thedown contacts open in sequence at predetermined distances from the door.These contacts are included in series in the down stopping circuit 21.

The control relay E is a current responsive relay of the moving coiltype with an adjustable drop out. It has a stationary coil ES connectedacross the supply conductors L2 and L3 for the hoisting motor H and itsmoving coil E is connected in series with the secondary winding of acurrent transformer CT the primary winding of which is connected withthe supply conductor L2 for the motor H. The control relay F is similarto relay E and its coils are connected to the supply conductors in thesame manner.

Inasmuch as moving coil relays are old and well known in the art, nofurther description thereof will be given, but if further detailedinformation is desired, reference may be had to Patent No. 1,820,712,issued to Walter Schaelchlin on August 25, 1931, and assigned to theWestinghouse Electric 8: Manufacturing Company, which patent shows amoving coil magnetic device which is used as a regulator but which maybe used as a relay for controlling any circuit, as desired.

The normally open contacts of the control relays are disposed in theshunt circuits 30, 3l, 32 and 33.

The relays E and F are so designed and adjusted that both of them willbe energized to close their contacts when the car starts, because of thelarge amount of current used in accelerating the car. The relay F isdesigned to drop out and open its contacts FI and F2 in the shuntcircuits 3| and 32 when the amount of current taken by the hoistingmotor decreases beyond a predetermined value as the load on it decreasesby reason of decrease of the elevator loading and the influence of thedirection of elevator operation. The relay E is designed and connectedto' drop ou-t and open* its contacts El and E2 in the shunt circuits 30and 33 when the current taken by the motor decreases still further byreason of still less loading of the elevator and the influence of thedirection of elevator operation.

The direction of operation of the car influences the load on the motor,as the counterweight is usually heavier than the empty car. The usualpractice is to load the counterweight so that it equals the weight ofthe empty car and then add to the counterweight a weight equal to 40% ofthe normal load for which the car is designed. For example, with a carweighing 5,000 pounds designed to carry a load of 2500 pounds thecounterweight would be ilrst loaded with 5,000 pounds to equal theweight of the car, and then an additional thousand pounds (40% of the2500 pounds load for which the car was designed) would be added to thecounterweight, making the total weight of the counterweight 6,000pounds, while the car without load would weigh 5,000 pounds, but withfull load would weigh '7500 pounds.

With the above described weighting of the counterweight, the car withfull load in the up direction will be a heavy load for the motor thanmedium load on the motor because the counterweight helps to pull the carupwardly thus causing the motor to use less than the medium amount ofcurrent. A car running in the down direction with full load will causethe motor to pull the least amount of current. Under these circumstancesthe relay F may be so designed and adjusted that it will open itscontacts when the motor is responding to that condition between an emptycar down and a balanced up or down car, and the relay E may be designedand adjusted to open its contacts when the motor is responding to acondition between a balanced up or down car and a full load down, asindicated by the curve in Fig. 3.

In the usual system, stops initiated at a definite point in the approachof the car to the floor with a medium strong brake, may vary as much asfive inches with the load range. For example, an empty car down may stopone and one-half inches above the landing floor and a loaded car downmay stop as much as three inches below the landing floor. With mysystem, the control relays and the diilerent positions of -the inductorplates may be used to vary the point at which the motor is cut off andthe brake applied in accordance with the load on the car or motor andits direction of operation so that stops with loads up to 60% will notvary more than three-fourths of an inch from the floor level and stopswith greater loads up to full load will not exceed one inch from iioorlevel.

It is believed that the invention may be best understood from an assumedoperation of the apparatus described. It will be assumed now that thecar is in the lower part of the shaft and is fully loaded and that theattendant in the car has rotated the car switch in counterclockwisedirection, thus energizing the relay M and the up direction switch tostart the car upwardly by the circuit L+, M, U, 31, 36, L-. Theenergized up direction switch closes its contact members Ui, U2 and U3and the energized relay M closes its MI, M2 and M3. The closing of thecontacts UI and U2 and MI, M2 and M3 causes the operation of thehoisting motor H by energizing its field windings 2l, 22, and 23, thecircuit extending through the conductor Li, Mi, UI, 2l, to a point 39,through the conductor L2, CT, M2, U2, 22 to the point 39 and throughconductor L3, M3, 23, to the point 39. The closing of the contacts UIand U2 and Mi and M2 also energizes the brake winding I8 to release thebrake Il. The closing of the contacts U3 provides a self-holding circuitfor the up direction switch U and the car running relay M through the upstopping circuit 29. These contacts U3 may be termed the holding meansfor causing the car to keep in motion after the car switch has beencentered for a stop until the stopping circuit is deenergized and thebrake applied.

The energization of the motor and the release of the brake causes thecar to move upwardly. The control relays E and F are also fully energzedbecause the motor is pulling a heavy current in accelerating the car.

It will be assumed now that, as the loaded car approaches the thirdfloor in the up direction, the attendant centers the car switch CS tocause the car to stop at the third iloor.

The centering of the car switch closes its contacts 35 and 36, therebyenergizing the coils A, B and C of the inductor relays AR, BR. and CR onthe car by the circuit L+, A, B, C, 35, 36, L-.

As the loaded car approaches the third floor with its inductor coilsenergizedI both control relays E and F will remain energizedsufficiently by the heavy current being pulled by the hoisting motor toprevent them from opening, and hence, their contact members El and FI inthe stopping circuit 29 will remain closed. However, this will notinitiate the stopping of the car. Inasmuch as the car is fully loaded,it will be easily stopped, but the hoisting motor will be pulling such aconsiderable amount of current, that the relays E and F will remainenergized, and, consequently, their contacts El and FI in the stoppingcircuit will remain closed. Hence, when the up car nears the third floorand causes the contacts AU to open rst. that does not affect thestopping circuit because the contacts Fl are closed, providing a shuntcircuit around the contacts AU. Inasmuch as the relay E remainsenergized, its contacts El are closed, and as the car approaches stillcloser to the iloor, its contacts BU are opened by the plate BUP1 butthe up direction switch still remains energized because the contacts Elstill remain closed in the circuit 26. As the car comes still cio-ser tothe floor, the inductor relay contacts CU come opposite the up plate CUPand are opened thereby. The opening of the contacts CU deenergizes theup direction switch U, and the car running relay M to open their contactmembers and thus deenergize the hoisting motor H and the brake coil l0of the brake Il. The cutting oil' of the motor decelerates it and thedeenergization of the brake il causes it to be applied to the hoistingdrum I2 to stcp the car. The car with its heavy load does not drift veryfar, but, inasmuch as its inductor relay contacts have been cut off atthe proper drift distance from the floor, the car stops approximatelylevel with the iloor.

Let it be assumed now that an up stop is made with the car loadedsufiiciently to balance the weight of the counterweight. Under suchcircumstances, the approach of the car to its third floor stop willcause the control relay F to drop out by reason of the lower amount ofcurrent pulled by the hoisting motor, and thus the contacts are open inthe shunt circuit around the contacts BU. As the car nears the oor underthese conditions, the up contacts AU come opposite the up plate AUP andare opened in the control circuit 29, but this does not affect the updirection switch because the control contacts El are still closed. Asthe car with its balanced load continues its approach to the third oor,the up contacts BU on the relay BR come opposite the up plate BUP andare opened in the up stopping circuit 29. This opening of the contactsBU deenergizes the up direction switch U because the contacts Fl areopen. The deenergizing of the up direction switch U and the car runningrelay M cuts ofi" the motor and applies the brake while the car is at apredetermined distance from the third floor, which distance is thepredetermined distance from the oor at which the car with a balancedload will drift into and stop approximately level with the floor afterits motor is cut oil' and its brake is applied.

Assuming now that the car is making the same up stop without any load.Inasmuch as the counterweight is heavier than the empty car, it ispulling the car up the hatchway without the assistance of the hoistingmotor H, and, hence, the car will require a greater distance in which todrift to a stop after the motor is cut ofi and the brake is applied thanit would if the car were balanced or were loaded to full capacity. Thecontrol relays E and F will both be opened, thus opening their contactsEl and Fl in the control circuit 29. As the empty car approaches the upstop at the third floor, its contacts AU come opposite the plate AUP andare opened in the stopping circuit 29. Inasmuch as the contacts Fl areopen, the opening of the contacts AU deenergizcs the up direction switchU and the car running relay M to cut off the motor and apply the brakeat the predetermined distance from the third oor at which the empty upcar will drift into and stop approximately level with the third oor.

It will be assumed now that the car not loaded is above the third floor,and that the attendant moves the car switch in counterclockwisedirection to cause the car to move downwardly towards the third oor.'I'his movement of the car switch closes its contacts 33 and 3l, therebyenergizing the car running relay M and the down direction switch D bythe circuit L+, M, D, 34, 36, L The energized relay D closes its contactmembers DI, D2, and D3. The closing of the contact members D3establishes a self-holding circuit for the down direction switch Dthrough the normally closed inductor relay contacts AD, BD, and CD toL-.

It will be assumed now that the attendant on the car centers the carswitch CS to cause the car to make a down stop at the third oor. Thecentering of the car switch energizes the inductor coils A, B, and C, aspreviously described to cause the car to stop at the third floor.

As the empty car approaches the down stop at the third floor, the downcontacts CD of inductor relay CR first approach the down inductor plateCDP and are opened thereby. The contacts CD are in the stopping circuit21, but inasmuch as the empty car down is causing the hoisting motor topull considerable current to move it downwardly by reason of the factthat the counterweight is heavier than the empty car, the control relaysE and F are closed, thus their contacts E2 and F2 are closed in thecircuits around the contacts BD and CD. Therefore, the opening of thecontacts CD does not aiTect the energization of the down switch D.

As the empty car approaches still closer to the down stop at the thirdoor, the contacts BD of the inductor relay BR are opened as they comeopposite the down inductor plate BDP. However, inasmuch as the contactsE2 are still closed, the opening of the contacts BD does not affect thestopping circuit 21.

As the empty down car approaches still closer to the third floor, thecontacts AD come opposite the plate ADP and are opened thereby, thusopening and stopping circuit 21 to deenergize the car running relay Mand the down direction switch D. The deenergization of the downdirection switch D and the relay M cuts 01T the hoisting motor H andapplies the brake I1 to stop the car, and this action takes place atjust the right distance from the third floor to cause the empty car withits motor cut 01T and its brake applied to drift into and stopapproximately level with the third floor landing.

It will be assumed now that the car is on a down trip above the thirdfloor, and is partly loaded with passengers whose weight plus that ofthe car balances the counterweight so that the car is in a balancedcondition. It will also be f' assumed that the attendant centers the carswitch as before described to cause the car to stop at the third iloor.Under these conditions, the hoisting motor H will be pulling such a.current that the control relay F will have dropped out and the controlrelay E remains energized, thus leaving the contacts F2 open and thecontacts E2 closed in the stopping circuit 21.

As the car approaches within a predetermined distance of the down stopat the third oor, the contacts CD come opposite the down plate CDP andare opened, but inasmuch as the contacts E2 are closed in the stoppingcircuit 21, thus the opening of the contacts CD has no effect on thecar. As the balanced car approaches closer to the down stop at the thirdfloor, the contacts BD come opposite the down plate BDP and are opened.Inasmuch as the contacts F2 are open, the opening of the contacts BDdeenergizes the down direction switch D and the car running relay M,thereby cutting off the motor H and applying the brake l1 to stop thecar. This action takes place at the predetermined distance from thethird floor which will cause the car with a balanced load to drift intoand stop approximately level with the third oor.

It will be assumed now that the car with full load is above the thirdfloor and that the attendant in moving it down, centers the car switchto cause another down stop at the third floor. The centering of the carswitch energizes the inductor coils A, B, and C, as previouslydescribed, and inasmuch as thel car is heavily loaded and is movingdown, the hoisting motor has little work to do. Therefore, both thecontrol relays E and F are deenergized to open their contacts E2 and F2.As the car approaches the down stop at the third floor, the contacts CDare rst opened by the inductor plate CUP thus deenergizing the downdirection'switch D and the car running relay Mr to cut off the motor andapply the brake to stop the car. The tendency of the fully loaded car,of course, is to move downwardly thus requiring a long drift into thelanding and it will be obvious that the contacts CD have opened at theright distance from the lioor to permit the car to drift in and stoplevel with the floor.

The curves in Fig. 4 are provided to illustrate the action of myinvention in correcting the accuracy of the stops at the floors. Thehorizontal line 40 represents a floor level. Ordinates measuredvertically from this line to the curve lines indicate the inaccuracy ofstop for various loads. Light load accuracies, including that for emptycar, are shown on the left side; those for heavy loads, including fullload, are shown on the right. Balanced car occurs to the left of thecenter. With balanced load the car stops level and the oor level line 40and the accuracy line 4l cross here, indicating no inaccuracy.

superimposed on line 4| is a broken solid line 42 to show the effect onthe accuracy of stopping when my invention is applied. Empty cars causestops 1/ inch high and light loads cause stops to 1/2 inch low. At acertain load, which is approximately half-way between empty car andbalanced load, the first correction occurs with the opening ci F. Stopsare initiated by contacts BU and BD, and, with loads in excess ofbalanced car accuracies, are produced in the range of 1% inch high to 3Ainch low. When sufficient car load occurs to cause the second correctionto occur by opening E, then loads to full load cause inaccuracies in therange of 1 inch high to 1 inch low, as indicated by curve 43.

The corrections could be caused to occur at other loads. With slightlydiierent plate locations, all loads could be caused to stop in a rangeof 3A inch high to 3A inch low. I prefer the adjustment indicated. Inthe average elevator approximately 60% of the loads carried are lessthan balanced car and an additional 30% approximately are betweenbalanced car and 3A load. With this adjustment, the greatest accuracy ofstopping is obtained with the loads that occur most frequently.

The circuits are, for the sake of simplicity, shown as those of a carswitch start system with automatic stop by a stopping inductor, but theinvention may be applied to any push-button f control system where thepush-buttons are used to start the car, a selector determines when itshould be stopped, and a car carried inductor relay stops it.

Although I have illustrated and described only one speciiic embodimentof my invention, it is to be understood that changes therein andmodifications thereof may be made without departing from the spirit andscope of the invention.

I claim as my invention:

1. In an elevator system, a car serving a plurality of floors in ahatchway, a motor for operating the car, means for energizing the motorby connecting it to a source of electrical energy, a plurality of switchdevices mounted on the car, means mounted on the wall of the hatchwayadjacent to each floor for eiTecting operation of the switch devices inconsecutive order as the car approaches a stop at a oor, a controldevice controlled by the loading of the motor, and means responsive toconsecutive operation of the switch devices when a stop is to be madeand to the condition of the control device for deenergizing the motorwhen the car approaches within a. predetermined distance of the floor atwhich the stop is to be made proportional to the loading of the motorand its direction of operation.

2. In an elevator system, a car serving a floor in a hatchway, a motorfor operating the car, means for energizing the motor by connecting itto a source of electrica1 energy, a plurality of switch devices mountedin side by side relation in a horizontal plane on the car, means foroperating the switch devices '1n consecutive order lwhen the carapproaches a stop at the floor, a

control device controlled by the loading of the motor, and meansresponsive to the consecutive operation of the switch devices when astop is to be made, and to the operation of the control device fordeenergizing the motor when the car approaches within a predetermineddistance of the floor at which the stop is to be made proportional tothe loading of the motor and its direction of operation.

3. An elevator system comprising a car operable to servie a plurality offloors in a hatchway, a motor for operating the car, switch means forconnecting the motor to a source of electrical energy, and a stoppingmeans for deenergizing the motor comprising a plurality of stoppingrelays mounted in side by side relation in a horizontal plane on thecar, a plurality of inductor plates for each floor for operating therelays when the car is to stop thereat, means for mounting the inductorplates for each tioor in diierent positions corresponding to theloadings on the car and its direction of operation to effect operationof the relays in consecutive order when a stop is being made, a controldevice controlled by the loading of the motor, and means responsive tooperation of the control device and the consecutive operation of therelays for deenergizing the motor when the car approaches within apredetermined distance of a iloor at which a stop is to be made.

4. An elevator system comprising a car operable to serve a floor landingin a hatchway, a motor, means for energizing the motor to operate thecar, a plurality of stopping switches mounted in a horizontal plane onthe car, means for simultaneously preparing the switches for operationwhen a stop is to be made, means for operating the switches inconsecutive order as the car approaches a stop at the floor, a pluralityof stopping means controlled by said switches for effecting stopping ofthe car, and control means responsive to the loading of the motor forselecting the stopping means to be operated in accordance with theloading and direction of operation of the car.

5. An elevator system comprising a car operable to serve a landing floorin a hatchway, a motor for operating the car, an up direction switch forconnecting the motor for up operation, a down direction switch forconnecting the motor for down operation, a stopping circuit, for eachswitch, a plurality of stopping relays mounted in a horizontal plane onthe car for controlling the stopping circuits, each relay having a pairof contacts disposed in each stopping circuit, a plurality of shortcircuits disposed around portions of each stopping circuit, means forsimultaneously energizing the relays when a stop is to be made, aplurality of inductor plates mounted on the hatchway wall at differentdistances from the landing floor in proportion to diiferent loadings ofthe car for causing operation of the relays in consecutive order whenthe car approaches a stop at the landing floor, a pair of control relaysassociated with the hoisting motor and responsive to the load thereonfor controlling the shunt circuits around portions of the stoppingcircuits to render effective that relay which corresponds to the load onthe motor.

6. An elevator system comprising a car operable to serve a landing floorin a hatchway, a motor for operating the car, direction switches forconnecting the motor for operation, a plurality of stopping circuits, aplurality of stopping relays mounted side by side in a horizontal planeon the car for controlling the stopping circuits, means forsimultaneously energizing the relays when a stop is to be made at thefloor, a plurality of inductor plates mounted in the hatchway atdifferent distances from the landing floor in proportion to differentloadings of the car for causing operation of the relays in consecutiveorder, a plurality of control devices responsive to the load on themotor for controlling the stopping circuits to render effective thestopping circuit which corresponds to the load 0n the motor and itsdirection of operation.

'1. An elevator system comprising a car operable to serve a landingfloor in a hatchway, a motor for operating the car, an up directionswitch for connecting the motor for up operation, a down directionswitch for connecting the motor for down operation, a plurality ofstopping circuits for each switch, a switch means for selectivelyenergizing the direction switches to start the car and for preparingthem for deenergization when a stop is to be made, self-holding meansoperated by the direction switches for connecting the stopping circuitsto control the switches when the car is to be stopped at a iloor, aplurality of stopping relays mounted in a horizontal plane on the carfor controlling the stopping circuits, means for simultaneouslyenergizing the relays when a stop is to be made, a plurality of inductorplates mounted on the hatchway wall at different distances from thelanding floor in proportion to different loadings on the car and itsdirection of operation for causing operation of the relays inconsecutive order, a

pair of control relays associated with the hoisting motor and responsiveto the loading of the car and its direction of operation for controllingthe stopping circuits to render eiective that stopping circuit whichcorresponds to the load on the car and its direction of operation.

8. In an elevator, a hatchway, a floor landing in the hatchway, a cardisposed for operation in the hatchway to serve the landing, a motor foroperating the car, a brake for stopping and holding the car, a pluralityof switching devices mounted on the car, a plurality of switch-operatingdevices mounted on the hatchway wall in position to effect operation ofthe switching devices in consecutive order and at predetermineddistances from the landing as the car approaches a stop at the landing,a plurality of circuits controlled by the switches for eiecting thestopping of the motor and application on the brake, and control meansresponsive to the load on the motor for rendering effective the stoppingcircuit corresponding to the load on the car and its direction ofoperation to cause the car to land approximately level with the floor inmaking a stop thereat.

9. In a control system for a motor driving an elevator; means forstarting said motor to move said elevator; holding means associated withsaid starting means for causing said elevator to continue in motion;stopping means for said motor comprising a plurality of pairs ofmembers, each pair comprising a member movable with the motion of saidmotor and a stationary member cooperating therewith, any pair of membersbeing capable of rendering ineffective said holding means to cause saidmotor to stop; means for rendering all of said pairs of memberseffective to initiate a stop of said elevator at a selected floor; andmeans responsive to the load current to said motor for determining whichpair of members will initiate said stop. whereby said elevator will becaused to stop substantially level with said floor regardless of theload in said elevator.

WILLIAM F. EAMES.

